Preparation of alkali metal derivatives of organic substances



3 derivatives which 'costly to prepare.

Patented Sept. 5, 1939 PATENT OFFICE, 7

PREPARATION OF ALKALI METAL DER-IVA TIVES OF ORGANIC SUBSTANCES Norman D. Scott, Sanborn, and Virgil L. Hensley and Joseph Frederic Walker,

Niagara Falls,

N. Y., assignors to E. I. du Pont de Nemonrs a Company, Wilmington, Del, a corporation of Delaware No Drawing. Application April 9, 1936, Serial No. 73,598

13 Claims. (01. 260- 515) This invention relates to the use of highly reactive alkali metal addition compounds as intermediates in the preparation of alkali metal derivatives of acidic hydrogen containing organic compounds which either do not react directly with the alkali metal or else do so only with difficulty. This general type of metathesis reaction has already been the subject of much study. Ziegler et al., Ann. 4'73, 22 (1929), describes the use of potassium cumene,

l C Ha-C-C H3.

In Houben Weyl (1924) v. IV, p. 964, the preparation and use of lithium phenyl,

d and sodium benzyl, are described. Other alkalimetal compounds employed include lithium, sodium or potassium methyl, ethyl, butyl, etc. All of these alkali metal compounds are substitution are exceedingly diflicult and Certain ketones, which have no alpha hydrogen group, also form alkali metal derivatives, e. g., sodium benzophenone,

R-Na +CO2- RCOONa.

They also may be reacted with alkyl or aryl halides, thus:

atom adjacent to the carbonyl An object of the present invention is to provide a convenient and economical method for producing alkali metal organic compounds. A further object is to provide improved methods for organic synthesis, including the production of car- 5 boxylic acids, in which organic alkali metal compounds are utilized as intermediates. Further obiects will be apparent from the following description.

The above objects are attained in accordance with the hereindescribed invention by first preparing solutions of alkali metal addition compounds of polycyclic aromatic hydrocarbons, and reacting these addition compounds .with other organic compounds having relatively acidic hy- 15 clrogen atoms, whereby the desired; alkali metal compounds of said other compounds are formed. These alkali metal compounds then may be reacted with various reagents such as carbon dioxide, alkyl halides and the like, to prepare valuable products. In this method the alkali metal addition compounds of the polycyclic aromatic hydrocarbons thus serve as carriers for the alkali metal. By this means, the formation of the desired alkali metal compounds not only is facilitated but the alkali metal compounds thus formed generally are in a more reactive state than when prepared by direct reaction with the alkali metal. This increased activity facilitates and improves yields in further synthetic reactions.

The alkali metal derivatives used as alkali metal carriers in accordance with the present invention are obtained by the addition of alkali metals to aromatic polycyclic hydrocarbons such as naphthalene, diphenyl, anthracene, acenaphthene, retene and the like, includ ng their homologs. ,The method of producing these reactive and soluble sodium derivatives was first descr bed by Scott in U. S. Patent 2,027,000 and a continuation of this patent, U. S. Patent 2,019,832. Certain classes of ether solvents were found to have a very specific action in promoting. the reaction of a kali metals with aromatic hydrocarbons to form these intermediate addition products which according to the presentdnvention must be used in the dissolved-state in the ether solvents in which they have been prepared. Ethers which have been" found useful in preparing these alkali metal addition products include all polyethers and all mono ethers containing a CH3-0-- group and in which the ratio of the number of oxygen atoms to. the number of carbon atoms is not less than 1:4 and whose strucand its aromati in question.

By stable ethers may not react in some reversible reaction with the alkali metal and/or aromatic hydrocarbon since indications are that the ethers in effecting the reactions may to some extent take part in the reaction, but the ether must not be broken up or form irreversible reaction products. Thus, for example, ethylene oxide may be considered a hydrocarbon addition complex cyclic ether falling within the limitations given as diluting agents for the effective ethers. There is, however, a minimum concentration for the efiective ether in the noneilectlve solvents beyond which the reaction will not proceed. Thus, in general, the effective ether can be diluted with a non-reactive, non-effective hydrocarbon or ether up to four or five times its volume. If the dilution be as high as six to. ten times the volume of the effective ether, the reacton to form the alkali metal addition product willnot proceed.

By the use of these effective ethers alkali metals have been shown to add to aromatic hydrocarbons and certain containing more than one benzene nucleus as well n-methyl carbazol. Aromatic hyrocarbon will be illustrated particularly with respect to the reaction of naphthalenewith sodium, but it is to be understood that what is said thereonwill apply equally well to the reaction of other alkali metals and to any of the suitable naphthalene homologues and analogues and other systems which will allow these form.

Eflective ethers which fall within the specifications set forth above include dimethyl ether, methyl ethyl ether, ethylene glycol dimethyl intermediates to It is highly important that these efl'ective ethers be essentially free from more than traces of hydroxyl or other impurities, which react with sodium to give especially those I coat over" the surface of the metal, in order to get the addi- The sodium should itself be clean and have been preserved under some ethers: we do not mean that the condensed ring fourth inch inert solvent prior to use. The form of the sodium is immaterial, but cubes of the metal oneon an edge have been found quite satisfactory. Generally, even with the best of care in preparing the solvents, naphthalene and H Na H Na It is probable that this is an equilibrium reaction. It is also found that other isomeric disodium addition compounds are formed as evitreatment with carbon dioxide.

In view of the fact that the solution which is thus prepared, and contains one gram atom of free radical which may be represented by the formula:

H Na

The soluble addition compound may involve the combinationof disodium naphthalene with an extra molecule of naphthalene in some other manner. Its formula could be written,

naphthalene and dihydronaphthalene; with CO1, it will yield the sodium salts of dihydronaphthalene dicarboxylic acids along with an equivalent amass-1 the reaction between the polycyclic aromatic For example,- certain amino compounds are also eflective as hydrocarbons and alkali metals.

solvents for promoting these alkali metal addition reactions. These amino compounds, which are described in co-pending joint applications filed by N. D. Scott and J. F. Walker include the amines: trimethylamine, dimethyl ethylamine, and tetramethyl ethylene diamine and a variety of amino ethers having tertiary amino groups, such as dimethylamino dimethyl ether, dimethylaminoethyl methyl ether, diethylaminoethyl methyl ether, dimethylaminoethyl 'diether ofethylene glycol and diethylamino dioxan.

We will now proceed to describe the use of this sodium addition product of naphthalene as an intermediate or a form of dissolved sodium as a tool in the production of other sodium-carbon compounds, sodium-oxygen-carbon compounds and sodium-nitrogen compounds otherwise difficult to prepare. We have discovered that when compounds possessing relatively acidic hydrogen atoms are added to the green solution of sodium naphthalene in one of the efiective solvents, in general a metathesis reaction occurs in which the sodium atom is transferred to the position occupied by the acidic hydrogen with the formation of dihydronaphthalene as a by-product. The reaction between sodium naphthalene and acetylene is typical:

O. C. Dermer in Chemical Reviews, 14, 396 (1934) lists a series of weakly acidic compounds in a scale of descending acidities as follows:

1. Phenyl acetylene 7. Triphenyl methane 2. Indene 8. l-naphthyl diphenyl 3. Phenyl fiuorene methane 4. Fluorene 9. Diphenyl methane 5. Xanthene 10. Cumene 6. Methyl diphenyl 11. Toluene (phenyl toluene) l2.-Benzene 13. Ethane The following examples further illustrate the present invention:

Example 1 Triphenyl methane, 0.1 gram molecule, was slowly added at room temperature to a green those compounds. above di-.

solution of sodium naphthalene in the dimethyl ether 01 ethylene glycol made by adding 0.15 gram atom of sodium to 200 cc. of the ether containing 0.1 gram molecule of naphthalene. The color of the ether solution changed from green to brilliant red as the triphenyl methane was added. Carbon dioxide was then admitted until this red color was discharged. Water was added to dissolve out the sodium salt of triphenyl acetic acid. By acidification with dil. 1101, 23.3 grams or an 81.0% yield, of triphenyl acetic acid having an equivalent weight of 286 was obtained.

Example 2 Acetylene was'passed into a liter of dimethyl glycol ether at 15 C. containing the equivalent of 1.0 gram atom of sodium as sodium naphthalene. The green color was discharged after the requisite amount of acetylene had been absorbed with the simultaneous precipitation of monosodium acetylide as a while solid. The by-product 1,4 dihydr'onaphthalene remained dissolved in the ether. As soon as the sodium naphthalene had reacted completely, carbon dioxide was admitted and reacted to form sodium propiolate. This salt was taken into water, acidified, extracted from water into ether and the ether removed in a vacuum. Forty-eight gins. -of propiolic acid, 69% of theory, was recovered.

Example 3 Tertiary butanol, 1.0 gram molecule, was slowly added to a stirred solution of naphthalene, 1.0 gram molecule in 500 cc. of dimethyl glycol ether in which the naphthalene was slowly reacting with one gram atom of sodium to form the soluble green sodium naphthalene addition product. The rate of addition of the tertiary butanol was such that the green color of the reaction mixture was discharged practically as fast as it was formed, allowing only a faintly green color to build up in the dimethyl glycol either solution. The reaction was essentially quantitative, i. e., one gram molecule of tertiary butanol was required to completely discharge the green color, thereby indicating that the whole gram atom of sodium had been consumed. The slurry of sodium tertiary butylate obtained by distilling off the glycol dimethyl ether and adding petroleum ether, b. p. 40-60 C., was filtered, washed with more petroleum ether, and carefully dried. The equivalent weight of the dried sodium tertiary butylate by tritration was 8'7 .3.

Example 4 dioxide was passed through the reaction mixture. The sodium c-arboxylate formed was dissolved in water and the aqueous solution treated with HCl-to precipitate the free carboxylic acid. A yield of 9.8 grams of recrystallized fluorene-9- carboxylic acid was obtained, m. p. 224 C. and having a neutralization equivalent of 212.

Example 5 A'cetonitrile, 20.5 grams. was added to a solu- 0., was 38 grams.

to be 120.93.

Example 6 A quantity of standard solution of aniline in dimethyl glycol ether (0.240 molal) was titrated into a dilute solution of sodium naphthalene in the same solvent. 28 cc. of this aniline solution were required to completely discharge the green color which changed to a violet red toward the end of the titration and then finally to colorless.

The sodium content of the amount of naphthalene solution used was then determined by titrating the alkalinity as be ng qu valent to 32 cc. of 0.227 normal acid. The reaction ratio of aniline and sodium naphthalene is thus shown Example 7 One gram equivalent of phenyl acetic acid was added to a'solution of sodium naphthalene in dimethyl glycol ether equivalents of sodium. product was soluble and imparted a brilliant purple color to the solution. This solution then absorbed carbon dioxide to give the disodiinn salt of phenyl malonic acid. The isolated free acid had an equivalent weight oi 83 and a melting point of 153-4 C.-with gas evolution.

Other compounds tatively with sodium naphthalene and other alkali metal addition compounds of P lycyclic aromatic hydrocarbons include 'for example, capronitrile, pyrrole, pyrrolidine, piperidine, dibenzalacetonitrile, etc. It is evident from the foregoing examples that the method is applicable to the preparation oi the sodium derintive of any organic compound which will react with the sodium addition compound of an aromath: polycyclic hydrocarbon to replace a hydrogm atom of the organic compound with a sodium atom and obviously is not limited to the cases 111st cited.

In general, it may be stated that an alkali metal addition compound of a. polycyclic aromatic hydrocarbon will react with those, organic compounds which contain one or more hydrogen atoms which are more acidic in nature than the hydrogenatoms of the polycyclic aromatic hydrocarbon utilized and this reaction I'Blllts in a substitution of the acidic hydrogen atom or atoms by alkali metal, the replaced hydrogen atom taking the place of the alkali metal in the addition compound. Thus, using the sodium addition compound of may be represented:

The various organic compounds which thus may react with the alkali metal addition compounds of polycyclic aromatic hydrocarbons and which will react quantinaphthalene, the. reaction is obtaine with substantially atom with a sodium additi polycyclic aromatic hydrocarbon, said sodium adcarboxy acids, with alkyl halides and other organic halogen compounds and with various other compounds. I ese alkali metal substitution compounds prepared in accordance with tion generally are produced in for example, high yield of no polymer formation.

We-clalm:

1. The process for preparing an alkali metal organic compound by replacing at least one hydrogen atom of an organic compound with an alkali metal atom which comprises reacting an organic compound having a' replaceable hydrogen atom with an alkali metal addition com pound ofa polycyclic aromatic hydrocarbon, said alkali metal addition compound being dissolved in an activating solvent for the reaction.

2. The process for preparing an alkali metal organic compound by replacing at least one hydrogen atom of an organic compound with an alkali metal atom which organic compound having a replaceable hydrogen dition compound being dissolved in an activating solvent for the reaction.

3. The process iorpreparing organic compound by replacing an. alkali metal at least one hyon. 4. The process for replacing a hydrogen atom of a hydrocarbon with analkali metal atom to compound of a polycyclic aromatic hydrocarbon, said alkali metal addition compound being dissolved in an activating solvent for the reaction.

5. The process comprising reacting fluorene comprises reacting an on compound of a with a solution of the sodium addition compound of ,a polycyclic aromatic hydrocarbon said sodium addition compound being dissolved in an activating solvent for the reaction.

6. The process comprising reacting a solution or the alkali metal addition compound of a polycyclic aromatic hydrocarbon with an organic hydroxy compound said alkali metal addition compound being dissolved in an activating solvent for the reaction.

v,7. The process comprising reacting an alcohol with a solution of the alkali metal addition compound of a polycyclic aromatic hydrocarbon said alkali metal addition compound being dissolved in an activating solvent for the reaction.

8. The process comprising reacting a solution of the alkali metal addition compound of a polycyclic aromatic hydrocarbon with an amino compound selected irom the group consisting of primary and secondary amines said alkali metal addition compound being dissolved in an activating solvent for the reaction.

9. The vprocess comprising reacting a solution of the sodium addition compound of naphthalene with an amino compound selected from the group consisting of primary and secondary amines said sodium addition compound being dissolved in an activating solvent for the reaction.

10. The process comprising reacting aniline with a solution of the sodium addition compound of naphthalene said sodium addition compound being dissolved in an activating solvent for the reaction.

11. The process for replacing a hydrogen atom of a hydrocarbon with an alkali metal atom to produce an alkali metal substitution compound of. said hydrocarbon which comprises reactin said hydrocarbon with a sodium addition compound or a. polycyclic aromatic hydrocarbon, said sodium addition compound being'dissolved in an activating solvent for the reaction.

12. The process for replacing a hydrogen atom of a hydrocarbon with an alkali metal atom to produce an alkali metal substitution compound of said hydrocarbon which comprises reacting said hydrocarbon with a sodium addition compound of naphthalene, said sodium addition compound being dissolved in an activating solvent for the reaction.

13. The process comprising reaction fluorene with a solution of the sodium addition compound of a polycyclic aromatic hydrocarbon and reacting the resulting suspension of the sodium compound oi fluorene with carbon dioxide said sodium addition compound being dissolved in an activating solvent for the reaction.

NORMAN I). soon. vmom L, HANSLEY. JOSEPH mnnnnrc warm. 

